KR20190028541A - Turbocharger with non-lube hydraulic pressure bearing - Google Patents

Abstract

1. A turbocharger for an internal combustion engine, the turbocharger being supported by hydrostatic bearings (15, 16) both radially and axially by compressed air supplied from a compressor (11), and a separate boost compressor The pressure is boosted to a pressure sufficiently high to support the rotor of the turbocharger. The turbocharger hydrostatic bearings 15, 16 are damped using wire mesh or dispersive friction dampers 33, 41.

Description

Turbocharger with non-lube hydraulic pressure bearing

(US government license)

The present invention was made with the support of the United States government under contract number FA86500-14-M-2470 awarded by the United States Air Force. The US Government has certain rights in the invention.

The present invention relates generally to a turbocharger, and more particularly to a turbocharger with an oil-free hydrostatic pressure bearing having mechanical dampers.

The turbocharger is used to compress the air supplied to the engine by using high-temperature gas exhaust as driving force. The engine exhaust drives a turbine that drives the compressor to supply compressed air to the engine. The performance of the engine is improved due to compressed air.

Conventional turbochargers require a shaft support system that uses oil lubed bay rings according to the viscosity of the fluid to provide a hydrodynamic film to the bearing. The components on the shaft typically include a compressor rotor mounted on one end of the shaft and a turbine rotor mounted on the other end of the shaft.

In operation of the turbocharger, considerable radial and axial forces are produced by the compressor and turbine reacting to the housing through radial journal bearings and axial thrust bearings. This can typically be accomplished with a lubrication system of pressurized oil to remove heat and reduce rolling resistance. In the case of a turbocharger, the lubrication system requires an oil cooler and pump to apply sufficient pressure to the bearings while preventing the oil from coking. If the hydraulic pressure is lost or the oil is contaminated from the internal combustion engine (IC) engine, the bearing performance is degraded due to loss of lubrication or cooling, resulting in catastrophic failure of the turbocharger bearing system. Some improved high-temperature turbochargers employ an additional coolant system in the bearing housing to lower the temperature of the bearing and bearing fluid to prevent oil coking. Separate bearing lubrication systems add significant weight to aircraft for unmanned aircraft or such aircraft as UAVs.

The present invention advantageously provides a turbocharger that supplies compressed air to an internal combustion engine. The turbocharger includes a compressor driven by the turbine and a rotor supported radially and axially by hydrostatic bearings. The compressed air from the compressor is sent to a boost compressor that increases the pressure used in the hydrostatic bearings. The boost compressor may be driven by a power take-off shaft from an IC engine or from a separate motor such as an electric motor.

The hydrostatic bearings are non-lubricious and have no other fluids, but are designed to limit the overall weight of the turbocharger for use in lightweight aircraft such as UAVs whose weight is critical to performance and to expose them to high temperatures. Is used.

Hydrostatic bearings include journal bearings in the center of a turbo pump with an overhung compressor and turbine. Mechanical or friction dampers are used in journal bearings to provide damping of vibration. The mechanical dampers may be full hoop dampers or circumferentially spaced segments around the bearings. A distributed frictional damper in which small spherical members in a complete hoop are arranged can also be used.

A more complete understanding of the present invention, as well as the advantages and features thereof, will be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.
1 shows a schematic view of a turbocharger with non-lube hydrostatic bearings of the present invention.
2 shows a cross-sectional view of a turbocharger with non-lube hydrostatic bearings of the present invention.
3 shows a sectional view of a turbocharger with oil-free bearings of the invention and mechanical dampers with hydrostatic thrust bearings.
4 shows a cross-sectional view of a turbocharger with mechanical dampers having the oil-free bearings and balancing pistons of the present invention.
Figure 5 shows a cross-sectional view of a turbocharger with non-lube bearings of the present invention and dispersible friction dampers.
Figure 6 shows a cross-sectional view of a dispersible friction damper in the turbocharger of Figure 5;
Figure 7 shows a cross-sectional side view of one of the frictional dampers having a complete annulus.
Fig. 8 shows a second embodiment of a friction damper in which three arc portions are arranged around the housing.
Figure 9 shows a flow diagram of the flow into and out of hydrodynamic bearings and balance pistons.

The present invention is a turbocharger with an oil-free hydrostatic bearing and mechanical or dispersive friction dampers. The exhaust gas of the compressor is used as a working fluid for hydrostatic bearings with a boost compressor to achieve sufficient hydrostatic pressure load capacity and damping of the bearings. The present invention improves reliability and durability by eliminating temperature-sensitive oil lubrication, oil cooler, oil pump and bearing housing cooling systems of conventional turbochargers. This is accomplished by employing compressed gas (air) from the compressor to hydrostatically support the shaft. In order to reduce the overall power consumption of the system, the bearing supply system is pre-boosted by a turbocharger compressor and is then driven directly by the engine through an accessory withdrawal shaft 18 or by a small electric motor 19 driven by a small electric motor 19 Type compressor to boost the required operating pressure. In other cases, the overall power draw is relatively small and the impact on the internal combustion engine (IC) engine performance is minimized.

1 shows a diagrammatic view of a turbocharger with non-lube hydrostatic bearings. The turbocharger includes a compressor (11) and a turbine (12) connected to a conventional rotor (13). One or more radial hydraulic pressure bearings 15 and one or more axial hydraulic pressure (or thrust) bearings 16 support the rotor 13 in both radial and axial directions.

The hot exhaust gas from the internal combustion engine (IC) engine 14 is supplied to the turbine 12 which drives the compressor 11 through the rotor 13 to compress the air. Thereafter, the compressed air is delivered to the engine 14. A portion of the compressed air from the compressor 11 is extracted and supplied to the boost compressor 17 through the boost compressor inlet so that the compressed air is pressurized to increase the pressure to an amount sufficient to support the rotor 13 And supplied to the boost compressor 17. The outlet of the boost compressor (17) is in fluid communication with one or more hydrostatic pressure bearings (16).

The boost compressor 17 may be driven directly by the engine 14 via an accessory withdrawal shaft 18, an in-engine compression cylinder, or may be driven by a separate motor, such as an electric motor 19.

Hydrostatic fluid film bearings provide a number of advantages that make them particularly useful in high speed turbocharger shaft / rotor bearing systems. These advantages include the ability to support large loads, where the hydrostatic bearing load capacity is a function of the pressure drop across the bearing surface on which the hydraulic pressure acts; Long lifetime (theoretically infinite) by the surface not touching, and very large stiffness and damping coefficients that provide precise positioning and control.

The use of compressed air instead of oil as a working fluid in hydrostatic bearings for turbocharger applications also provides benefits such as the elimination of lubrication failure modes. Enabling operation at higher turbine inlet temperatures. It also reduces the thermal stress in the bearing housing by eliminating the cooling passages required to prevent the oil from overheating. As the operating temperature increases in lean-burn internal combustion engine engines, higher temperature bearings are required to support the rotor of the turbocharger. Small aircraft such as UAV require bearings that can withstand higher loads from start-ups, including continuous high-G turns and turbulent movements. Also, the hydrostatic bearings do not require the use of improved coatings because internal components are not rubbed after bearing lift-off occurs, so that high temperature materials including ceramics may also be used as the bearing material. The key advantage of hydrostatic bearings in high altitude turbocharger applications is that the boost pressure provided by the turbocharger compressor to pre-boost the inlet pressure of the small oil-free compressor to maximize the load capacity for all turbocharger operating conditions . The bearings lift off before or after ignition of the IC engine to enable wear-free operation over the entire operating range.

Another important advantage offered by hydrodynamic bearings is the control of precise tolerances that they can provide. This is especially important for maximizing the efficiency of turbochargers that require small diameter shroudless compressors and turbines that require minimal clearance (both radial and axial) to reduce leakage. Precise control of the shaft with high rigidity and damping makes hydrostatic bearings suitable for turbocharger applications in unmanned aerial vehicles.

Figure 2 shows a cross-sectional view of a turbocharger with lubrication oil-hydraulic bearings of the diagram of Figure 1; The turbocharger includes a compressor inlet 21 and a compressor outlet 22, a turbine inlet 23 and a turbine outlet 24, one or more journal bearings 25, a thrust bearing 26, a rotary journal 27, (28), a bearing-supply fitting portion (29), a V-band (30), and an airtight ground surface (31). The turbocharger has overhung compressor and turbine elements with bearings in the central housing and has a seal to seal the bearing chamber. The thrust bearing 26 is positioned at the center of the shaft to provide vents symmetrical with respect to each of the hydrostatic journal bearings 25. The design of the turbo of Figure 2 provides for simplification of the bearing chamber components. The design of the bearing is completely symmetrical with respect to the center plane of the thrust bearing 26, thus providing replica parts that are part-market upgraded with conventional produced turbochargers that do not have hydrostatic bearings themselves. One can replace the bearing housing of a conventional turbocharger with the hydrostatic pressure air bearing of FIG.

Figure 3 shows a turbocharger with a mechanical damper 33 disposed between the bearing housing 28 and the hydrostatic journal bearing 25. [ Mechanical friction dampers are wire mesh type. The hydrostatic thrust bearing 34 is located on the left side, and the axial friction stop 35 is located on the right side.

Figure 4 shows a turbocharger similar to the turbocharger of Figure 3, but with a balance piston cavity 36 on the left side. The mechanical friction dampers 33 are used in the same positions as in Fig.

In Figure 5, embodiments of a turbocharger use distributed frictional dampers in a full hoop arrangement. These friction dampers are small spherical elements that are damped by friction with each other within a confined space, or balls made of ceramic or metallic material. Figure 6 is a perspective view of a distributed frictional system with a closure 42, a snap ring member 43, a seal or lid plate 44 and a spring 45 for compressing frictional dampers 41 within a confined space. And a detailed view of one of the dampers 41 is shown. A clearance space 47 is formed between the bearing housing 28 and the floating journal bearing 25. The journals 46 are floating within the housing 28. The distributed frictional dampers 41 are formed of small spherical members that fill the full hoop space between the bearing and the housing while the bearing journal is being floated (the bearing is supported on the ground via the dampers). These spherical members may be metal or ceramic, and they act as dampers by rubbing against each other to exhibit a damping effect. Distributed friction dampers act like incompressible fluids and mimic oil squeeze film dampers.

The two frictional dampers 33 used in the embodiment shown in Figs. 3 and 4 are each made of a complete 360 mesh formed from a fine wire mesh fabric, such as a shock & vibration resistant device made by Metex Corporation (www.metexcorp.com) ° a ring type friction damper. 7 is a side view of a full annular friction damper 33 fixed between the bearing housing on the outer surface and the journal bearing 25 on the inner surface. The frictional damper 33 is donut-shaped. 8 shows a second embodiment of a friction damper in which three arc portions 51 equally spaced around the journal bearing 25 are used.

9 is a schematic flow chart of an air supply and ventilation system. A high pressure airflow is introduced through the orifice in the middle through the fitting 29. Thereafter, the airflow flows into the cavity in the center of the journal bearing 25 and the gap 47. If desired, a small portion of the airflow flows through the gap 47 to provide coolant to the dampers 41 or 33. The majority of the air flow is then separated from the bearing journal 25 by half of the airflow into the compressor side bearings and the other half into the turbine side bearings. After providing lift to the hydrostatic bearing the flow of air flows into the cavity 51 between the runner 27 and the shaft 13 through a series of orifices 60 in the runner 27, Pressure cavity into a low-pressure cavity 50 formed between the bearing 27 and the bearing journal 25. After entering the cavity 51, the airflow exits through a series of orifices 61 in the runner 27 and is finally discharged into the flow path 24 of the exhausted turbine. This air provides cooling behind the turbine rotor 12. The other half of the bearing flow escapes through the cavity 52 and out through the control orifices 62 to ambient pressure.

The flow of the unidirectional thrust bearing 34 or the thrust piston 36 is separated from the central pressure fitting portion 29 through the orifices 63 and flows into the cavity 53. The cavity 53 provides a thrust bearing or thrust piston through the orifices 64 into the thrust cavity 54. A small amount leaks from the cavity 54 into the compressor, the majority of which leaks into the cavity 52 and exits through the orifices 62.

It will be understood by those skilled in the art that the present invention is not limited to what has been particularly shown and described herein. It is also to be understood that, unless stated otherwise, all attached drawings are not drawn to scale. Various modifications and variations are possible in light of the above teachings without departing from the scope and spirit of the invention, which is limited only by the following claims.

Claims (13)

A turbocharger for an internal combustion engine,
A compressor for compressing air for combustion in the internal combustion engine;
A turbine for driving the compressor using the hot gas exhaust from the internal combustion engine;
A rotor connected between the compressor and the turbine of the turbocharger;
A first hydraulic journal bearing and a second hydraulic journal bearing for rotatably supporting the rotor in a radial direction;
A first vibration damper disposed between the first hydraulic pressure journal bearing and the bearing housing, and a second vibration damper disposed between the second hydraulic pressure journal bearing and the bearing housing;
An inlet connected to an outlet of the compressor for supporting the rotor and an outlet connected to the first hydraulic pressure bearing and the second hydraulic pressure bearing, wherein the pressure of the compressed air from the compressor to support the rotor is higher And a boost compressor for increasing the pressure of the internal combustion engine. The method according to claim 1,
Wherein the rotor comprises an axial thrust bearing of a hydraulic pressure supplied with compressed air from the boost compressor. The method according to claim 1,
Wherein the boost compressor is driven by the power take-off shaft from the internal combustion engine. The method according to claim 1,
Wherein the boost compressor is driven by an electric motor. The method according to claim 1,
Wherein the boost compressor is an additional compression cylinder in the internal combustion engine. The method according to claim 1,
Wherein each of the first vibration damper and the second vibration damper is a wire mesh damper. The method according to claim 1,
Wherein the first vibration damper includes a plurality of elements enclosed within a cavity formed between the first hydraulic journal bearing and the bearing housing;
Wherein the second vibration damper includes a plurality of elements enclosed in a cavity formed between the second hydraulic journal bearing and the bearing housing. 8. The method of claim 7,
Wherein the plurality of elements of each of the first vibration damper and the second vibration damper is a ceramic sphere composed of ceramic. 8. The method of claim 7,
Wherein the plurality of elements of each of the first vibration damper and the second vibration damper is a metal sphere composed of a metal. The method according to claim 6,
Wherein the wire mesh damper is a toroidal damper. The method according to claim 6,
Wherein the first vibration damper includes a plurality of segments circumferentially arranged around the first hydraulic journal bearing,
Wherein said second vibration damper comprises a plurality of segments circumferentially arranged around said second hydraulic journal bearing. ≪ RTI ID = 0.0 > 11. < / RTI > The method according to claim 6,
Wherein the wire mesh damper is cooled by using cooling air which is also used for cooling the first hydraulic journal bearing and the second hydraulic journal bearing. The method according to claim 1,
Wherein the compressed air used in the first hydraulic journal bearing and the second hydraulic journal bearing is also used to cool the hub side of the turbine rotor.

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